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. 2010 Dec 20;7(1):111.
doi: 10.1186/1742-4690-7-111.

Disease-associated XMRV sequences are consistent with laboratory contamination

Stéphane Hué  1 , Eleanor R Gray, Astrid Gall, Aris Katzourakis, Choon Ping Tan, Charlotte J Houldcroft, Stuart McLaren, Deenan Pillay, Andrew Futreal, Jeremy A Garson, Oliver G Pybus, Paul Kellam, Greg J Towers
Affiliations

Disease-associated XMRV sequences are consistent with laboratory contamination

Stéphane Hué et al. Retrovirology. .

Abstract

Background: Xenotropic murine leukaemia viruses (MLV-X) are endogenous gammaretroviruses that infect cells from many species, including humans. Xenotropic murine leukaemia virus-related virus (XMRV) is a retrovirus that has been the subject of intense debate since its detection in samples from humans with prostate cancer (PC) and chronic fatigue syndrome (CFS). Controversy has arisen from the failure of some studies to detect XMRV in PC or CFS patients and from inconsistent detection of XMRV in healthy controls.

Results: Here we demonstrate that Taqman PCR primers previously described as XMRV-specific can amplify common murine endogenous viral sequences from mouse suggesting that mouse DNA can contaminate patient samples and confound specific XMRV detection. To consider the provenance of XMRV we sequenced XMRV from the cell line 22Rv1, which is infected with an MLV-X that is indistinguishable from patient derived XMRV. Bayesian phylogenies clearly show that XMRV sequences reportedly derived from unlinked patients form a monophyletic clade with interspersed 22Rv1 clones (posterior probability >0.99). The cell line-derived sequences are ancestral to the patient-derived sequences (posterior probability >0.99). Furthermore, pol sequences apparently amplified from PC patient material (VP29 and VP184) are recombinants of XMRV and Moloney MLV (MoMLV) a virus with an envelope that lacks tropism for human cells. Considering the diversity of XMRV we show that the mean pairwise genetic distance among env and pol 22Rv1-derived sequences exceeds that of patient-associated sequences (Wilcoxon rank sum test: p = 0.005 and p < 0.001 for pol and env, respectively). Thus XMRV sequences acquire diversity in a cell line but not in patient samples. These observations are difficult to reconcile with the hypothesis that published XMRV sequences are related by a process of infectious transmission.

Conclusions: We provide several independent lines of evidence that XMRV detected by sensitive PCR methods in patient samples is the likely result of PCR contamination with mouse DNA and that the described clones of XMRV arose from the tumour cell line 22Rv1, which was probably infected with XMRV during xenografting in mice. We propose that XMRV might not be a genuine human pathogen.

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Figures

Figure 1
Figure 1
Alignment of XMRV gag-leader sequence with gag-leader sequences from endogenous MLVs in mice. XMRV-like sequences from four inbred mice containing the 24 nt deletion signature were identified by deep sequencing and one sequence identified by BLAST. The most similar sequences from the C57BL/6 genome are shown for comparison and all sequences are compared to XMRV VP62. Numbering refers to the length of the PCR product derived using primers EG87 and EG89 (Additional File 1; Table S1).
Figure 2
Figure 2
Phylogeny of 22Rv1 and patient derived XMRV sequences and other murine leukaemia viruses. Bayesian maximum clade credibility phylogeny of 22Rv1 cell line derived XMRV clones, patient derived XMRV sequences and other murine leukaemia viruses (A). The monophyletic cluster formed by 22Rv1 cell line derived XMRV clones and patient derived XMRVs is magnified in (B). Xenotropic MLV (MLV-X), polytropic MLV (PMLV), and modified polytropic MLV (MPMLV) were added as controls. Sequences derived from prostate cancer patients (VP and WO) and chronic fatigue syndrome patients (WPI) are indicated by red and yellow circles respectively. Gene sequences derived from 22Rv1 clones are indicated by blue squares. When full-length genomes were not available, the loci of the sequence used in the phylogenetic reconstruction are shown in brackets. APOBEC-3G/F hypermutated clones are labelled with a closed circle. The tree is rooted against AKV and Moloney MLVs. Bayesian posterior probabilities of 1.00 are indicated on the corresponding branches by a star. The scale bar represents the number of nucleotide substitutions per site.
Figure 3
Figure 3
Enumeration of nucleotide substitutions per site between the cell-line and patient-derived XMRV sequences . The pairwise genetic distance among pol and env sequences derived from 22Rv1 cells (white boxes) is significantly higher than among patient-associated sequences (grey boxes) (Wilcoxon rank sum test: p = 0.005 and p < 0.001 respectively). There is no significant difference in variation in the gag region. The top end of the y-axis was truncated to accommodate outliers in the gag 22Rv1 category. Outliers are due to APOBEC hypermutation.
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References

    1. Urisman A, Molinaro RJ, Fischer N, Plummer SJ, Casey G, Klein EA, Malathi K, Magi-Galluzzi C, Tubbs RR, Ganem D. et al.Identification of a novel Gammaretrovirus in prostate tumors of patients homozygous for R462Q RNASEL variant. PLoS Pathog. 2006;2:e25. doi: 10.1371/journal.ppat.0020025. - DOI - PMC - PubMed
    1. Lombardi VC, Ruscetti FW, Das Gupta J, Pfost MA, Hagen KS, Peterson DL, Ruscetti SK, Bagni RK, Petrow-Sadowski C, Gold B. et al.Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome. Science. 2009;326:585–589. doi: 10.1126/science.1179052. - DOI - PubMed
    1. Fischer N, Hellwinkel O, Schulz C, Chun FK, Huland H, Aepfelbacher M, Schlomm T. Prevalence of human gammaretrovirus XMRV in sporadic prostate cancer. J Clin Virol. 2008;43:277–283. doi: 10.1016/j.jcv.2008.04.016. - DOI - PubMed
    1. Dong B, Kim S, Hong S, Das Gupta J, Malathi K, Klein EA, Ganem D, Derisi JL, Chow SA, Silverman RH. An infectious retrovirus susceptible to an IFN antiviral pathway from human prostate tumors. Proc Natl Acad Sci USA. 2007;104:1655–1660. doi: 10.1073/pnas.0610291104. - DOI - PMC - PubMed
    1. Schlaberg R, Choe DJ, Brown KR, Thaker HM, Singh IR. XMRV is present in malignant prostatic epithelium and is associated with prostate cancer, especially high-grade tumors. Proc Natl Acad Sci USA. 2009;106:16351–16356. doi: 10.1073/pnas.0906922106. - DOI - PMC - PubMed

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